Bushing



Jan. 14, 1936. N. sKlLLMAN BUSHING Filed Feb. 5, 1931 #1m W//W`5 1 M n WMM? /4 BY l X M ATTO R N EY` Patented Jan. 14, 1936 PATENT OFFICE RUSHING Newton Skillinan,l Detroit, Mich., assgnor to O. & S. Bearing Company, Detroit, Mich., a corporation of Michigan Application February 5, 1931, Serial No. 513,484 4 Claims. (Cl. 308-238) This invention relates to a bushing, and has to do particularly with a novel, compact and simple self-lubricating bushing for use in steering columns and the like, and method oi iorming same.

The provisionv of an efcient bushing for steering columns has long been an important problem. 1n many cases the problem of assembly is a diincult one, in others, the bushing must be held to either one or two very accurate dimensions and, furthermore, the bushing must stand up under continued wear and prevent rattling. One type of bushing that has proven satisfactory for use in steering columns is that described in Patent No. 1,141,974 oi June 8, 1915. While such bushings are comparatively inexpensive they require spinning or preiorming of the lubricant impregnated lining so as to be correctly compressed and sized when iltted on a steering colu umn or shaft of a certain size. Furthermore, While the metal sleeve is very easy to form, -it does present limitations as to the size or tubing with which it can be used.

It is an object of the present invention to provide a bushing having an outer portion lformed 'of initially plastic material allowed to harden and a lining of lubricant impregnated fibrous material carried and held to a predetermined dimension by the hardened outer material.

The hardened material forming the outer part of the bushing is novel in itself in that it acts as an insulator when used in steering column assemblies having a solid shaft and it also permits the bushing to be assembled without the necessity of reaming the housing. Standard tubing can be used for the cuter housing of the steering column thus materially decreasing' the overall cost of the steering vcolumn as a unit. Another feature resides in the fact that the' outer hardened material is such that the sur-v face thereof will shear oil during assembly and Without in any way changing the insideidiameter of the bushing.

-Other features reside in the method of form- :ing my novel bushing wherein the lubricant impregnated brous lining is rst assembled on an arbor of predetermined diameter and the initially plastic material then positioned around the iibrous material, formed, and allowed to set; the plastic material having entered the interstices of the fibrous lining whereby when such plastic material is set it ilrmly holds the ilbrous lining compressed and in nal position; in other words, whenthe arbor is removed after the setting and cooling of the bushing the interior dimension of the lubricant impregnated fibrous lining is` accurately predeterminedand maintained. The necessity of spinning the lining Lto size is eliminated. Another feature of the method is that the entire bushing unit is formed in'one operation.

@ther features reside in details of construction of the bushing, particularly of the adaptation ci the same to a solid shaft, and in details of the method of forming the same, as will be more clearly brought out in the specification and claims.

ln the drawing:

Fig. l is a perspective, somewhat diagrammatic view, of the preferred manner of roughly 1;, prelorming the plastic material prior to assemn bly around the xedly positioned lining.

Fig. 2 illustrates the step of the method wherein the fibrous lining is stretched over the arbor. 20

Fig. 3 illustratesthe step of assembling the plastic pellets around the fibrous material prior to compression and setting ci this plastic material. A

Fig. Ll is a view similar'A to Fig. 3, but showing the dies in closed position for giving the bushing its iinal finished shape in one operation.

Fig. 5 illustrates the step of removing the arbor to produce the finished bushing as shown in Fig. o. Y

Fig. 6 illustrates a finished bushing.

Fig. l is a fragmentary enlarged sectional view taken through my nished bushing and illustrating the manner in which the plastic material impregnates and binds the fibrous lining.

In forming my bushing I preferably select an arbor l of predetermined diameter according to the size of bushing desired. A lining of woven brousmaterial stitched together as at 2 to form an annular liner 3 is next stretched over 40 the mandrel as indicated in Fig. 2. This liner 3 may be formed as described in mywPatent No. 1,731,988 of October 15, 1929, or this fibrous material may be formed and impregnated with graphite in any other suitable manner.

The plastic material forming the main body oi my bushing is preferably composed of a mixture of 60% gilsonite, 25% cotton linters and 15% clay. It will be understood, however, that different forms and percentages of plastic mate- 50 rials may be utilized, the essential feature being that the material is applied in plastic form and allowed to set or harden to form the nlshed bushing.

In the preferred manner of carrying out my invention the plastic material is iirstroughly formed into plastic pellets each pellet being formed of two halves, as best shown in Fig. 1. The plasticity of the pellets may obviously vary considerably and it will also be obvious that the temperature of plasticity may vary considerably according to the materials making up the plastic mass. i

Any suitable dies may. be utilized in forming the bushing and in Fig. 3 I have shown somewhat diagrammatically a set of water cooled diesconsisting of upper and lower die members 4 and 5 and end die members 6 and l.

One half of a preferably hot plastic pellet is placed in the corresponding cavity in the die, the arbor with the fabric fibrous lining then placed in position in the pellet half and the assembly completed by placing the top pellet of plastic material in place. The end dies 6 and 1 may or may not be brought together, depending upon the particular bushing being formed, but regardless of this the main die blocks 4 and 5 are brought together with the application of approximately one thousandk pounds pressure per `square inch. This pressure places the plastic material under compression and, in addition to placing the fibrous liner 3 under compression, the plastic material is such as to fill the interstices of the fibrous liner. The die blocks are preferably cooled and with the application of pressure and cooling the plastic material will quickly set or harden with the result that the plastic material flowing into the interstices of the iibrous lining will also harden and thus rmly join and permanently hold the fibrous liner in the position it assumes around the mandrel. Upon separation of the die' blocks, the initially plastic material will be set as indicated at 9 to form a nished bushing I0. 'Ihe mandrel I may be very easily removed from the bushing with the result that a bushing has been formed in one operation and whose inner layer is of fibrous material. Thus, while the inner liner 3 has been placed under compression during the formation of the bushing its inner dimensions determined by the mandrel 4I are positivelyv determined and maintained by the hardened plastic material.

Where the shaft of the steering column is solid it is often' desirable to have some form of. electrical connection connected to or passing through the bushing. In order to take care of this problem I preferably form a small aperture II longitudinally of the bushing. This aperture may be formed by means of suitable plunger I2 forming a part of the die structure.

A metal ring I3 of conductive material may be positioned in place and pressed into one end .of the bushing, as best illustrated in Figs. 3

and 4. The passageway II formed in the bushying preferably cooperates with a suitable aperture in this ring member I3. An electrical conduit I4 may then be passed through the passageway Il and connected to the ring I3 by soldering or otherwise. It will thus be obvious .i

that the metal ring I3 may be easily contacted, with a horn button or other device forming a." part of the steering column with the result that electrical connection can be easily made at the base of the steering column.

It will 'thus be obvious that any number of sizes or passageways may be formed in the wall of the bushing in addition to the opening defined by the fibrous liner. The heated plastic material will puter the portion of the fibrous liner, when placed under compression, as best illustrated in Fig. 7 and when such material sets it will positively hold the shape and dimensions 10 as predetermined by the arbor I. I prefer to compress the plastic material radially but it will be obvious that it may bev compressed under longitudinal pressure, the dimculty here being that there is some liability of the fibrous liner being pressed down 'or distorted' when pressure is applied to compress the plastic material.

When my novel nished bushing is installed in position within the steering column or similar assembly the inner diameter of the liner is, of course, fixed so as to have a certain definite relation relative to the shaft; however, the outer diameter of the bushing may vary considerably as if the housing is rough or if too small the outer surface of the bushing will just shear off instead of cracking.

d The material used in the outer portion of my bushing is particularly advantageous for use with steering columns in that it is waterproof and will not expand or crack under the `action of moisture. The main ingredient for the heated plastic material used for the outer portion of' my bushing is asphalt or an asphaltic compound. When set it is relatively non-frangible Aand will shear oir relatively easily when inserted in the steering column housing. It is also of such solidity as to maintain the given diameter of the inner iibrous liner regardless of the pressure applied to the exterior of the bushing 40 during and after assembly.

What I claim is:

1. A bushing comprising an inner liner of lubricant impregnated ilbrous material integrally' backed and held in place by a hardened asphaltic material, said material being of such consistency as to readily shear when forced into an undersize housing unit.

2. A bushing comprising' a self-lubricating liner and a surrounding body of asphaltic ma- 60 terial forming a spacer to complete the bushing unit, the material of said liner and body being mechanically interlocked to form an integral unit.

3. A bushing comprising a liner o f lubricant impregnated fibrous material and an outer body of moldable material adapted to harden by cooling, said material being formed mainly of asphalt.

4. A steering column Ibushing comprising an 00 inner liner of self-lubricating material, an outer body of asphaltic insulating material of the type adapted to harden by cooling, a contact ring positioned inone end of said outer body, and an electrical conductor connected to said ring and I 5 passing through said body of insulating material.

NEWTON SKILLMAN. 

